
Metropolitan Police spokesman Colonel Piya Uthayo yesterday said police expected at least 10,000 protesters to join the rally.
While the protesters plan to congregate at Sanam Luang and then march to the Royal Plaza, Piya said they should not head to the Royal Plaza before 7pm, as the Royal Guards will be rehearsing for the trooping of the colours earlier in the day.
The protesters are expected to disperse at midnight.
Some 150 police officers will be deployed at Sanam Luang, 150 at Democracy Monument and 150 at the Royal Plaza, while another 150 will take care of traffic in the area. A further 300 officers will be held back in case support is needed.
Police will ask the military for more support if necessary, Piya said, adding that roads would remain open to traffic unless the size of the rally exceeded expectations.
The PAD said it would march in protest against fugitive ex-prime minister Thaksin Shinawatra accepting an advisory position offered by Cambodian Prime Minister Hun Sen.
The PAD said its protest would also be an expression of loyalty to the Royal Family and to show its readiness to protect the country's dignity.
Sunthorn Raknarong, a PAD coordinator in the 16 southern provinces, said many protesters from the South had started travelling to Bangkok by car yesterday. They plan to offer get-well wishes to His Majesty the King at Siriraj Hospital before joining the rally.
However, most southern protesters will travel by train, he said.
Sunthorn said at least 500 protesters from each of the southern provinces had volunteered to join the rally.
Suriyan Thongnu-ied, secretary-general of the Campaign for Popular Democracy, said PAD supporters from Chiang Mai would either travel on their own or take vans provided by the PAD.